London - British Airways said it
had cancelled all flights from London's Heathrow and Gatwick
airports scheduled before 1700 GMT on Saturday due to a global
computer outage.
"We have experienced a major IT system failure that is
causing very severe disruption to our flight operations
worldwide," the airline said in a statement.
Passengers at Heathrow Airport reported long lines at check-in counters and flight delays. One posted a picture on Twitter of BA staff writing gate numbers on a white board.
"We've tried all of the self-check-in machines. None were working, apart from one," said Terry Page, booked on a flight to Texas. "There was a huge queue for it and it later transpired that it didn't actually work, but you didn't discover that until you got to the front."
The problem comes on a holiday weekend, when thousands of Britons are travelling.